Pain leads to compliance. Injury leads to the kinds of maladays that are explained above. You need to know the difference in the pain of a pin vs hurting because of an injury.

What hooked me on aikido was that first nikyo. Whew, what pain and no injury!!!! I just had to learn how to do that. After a while I learned the difference between making it hurt and learning about control. Now, I focus more on control than making it hurt. But pain is what makes believers out of people that think its a dance.